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Posted to github@arrow.apache.org by GitBox <gi...@apache.org> on 2022/05/10 20:18:07 UTC
[GitHub] [arrow-rs] alamb commented on a diff in pull request #1684: simplify offsets checking
alamb commented on code in PR #1684:
URL: https://github.com/apache/arrow-rs/pull/1684#discussion_r869644804
##########
arrow/src/array/data.rs:
##########
@@ -1033,72 +1035,61 @@ impl ArrayData {
}
/// Calls the `validate(item_index, range)` function for each of
- /// the ranges specified in the arrow offset buffer of type
+ /// the ranges specified in the arrow offsets buffer of type
/// `T`. Also validates that each offset is smaller than
- /// `max_offset`
+ /// `offset_limit`
+ ///
+ /// For an empty array, the offsets buffer can either be empty
+ /// or contain a single `0`.
///
- /// For example, the offset buffer contained `[1, 2, 4]`, this
+ /// For example, the offsets buffer contained `[1, 2, 4]`, this
/// function would call `validate([1,2])`, and `validate([2,4])`
fn validate_each_offset<T, V>(
&self,
- offset_buffer: &Buffer,
+ offsets_buffer: &Buffer,
offset_limit: usize,
validate: V,
) -> Result<()>
where
T: ArrowNativeType + std::convert::TryInto<usize> + num::Num + std::fmt::Display,
V: Fn(usize, Range<usize>) -> Result<()>,
{
- // An empty binary-like array can have 0 offsets
- if self.len == 0 && offset_buffer.is_empty() {
- return Ok(());
- }
-
- let offsets = self.typed_offsets::<T>(offset_buffer)?;
-
- offsets
+ let offsets = self.typed_offsets::<T>(offsets_buffer)?
.iter()
- .zip(offsets.iter().skip(1))
.enumerate()
- .map(|(i, (&start_offset, &end_offset))| {
- let start_offset: usize = start_offset
- .try_into()
- .map_err(|_| {
- ArrowError::InvalidArgumentError(format!(
- "Offset invariant failure: could not convert start_offset {} to usize in slot {}",
- start_offset, i))
- })?;
- let end_offset: usize = end_offset
- .try_into()
- .map_err(|_| {
- ArrowError::InvalidArgumentError(format!(
- "Offset invariant failure: Could not convert end_offset {} to usize in slot {}",
- end_offset, i+1))
- })?;
-
- if start_offset > offset_limit {
- return Err(ArrowError::InvalidArgumentError(format!(
- "Offset invariant failure: offset for slot {} out of bounds: {} > {}",
- i, start_offset, offset_limit))
- );
- }
-
- if end_offset > offset_limit {
- return Err(ArrowError::InvalidArgumentError(format!(
- "Offset invariant failure: offset for slot {} out of bounds: {} > {}",
- i, end_offset, offset_limit))
+ .map(|(i, x)| {
+ // check if the offset can be converted to usize
+ let r = x.to_usize().ok_or_else(|| {
+ ArrowError::InvalidArgumentError(format!(
+ "Offset invariant failure: Could not convert offset {} to usize at position {}",
+ x, i))}
);
+ // check if the offset exceeds the limit
+ match r {
+ Ok(n) if n <= offset_limit => Ok(n),
+ Ok(_) => Err(ArrowError::InvalidArgumentError(format!(
+ "Offset invariant failure: offset at position {} out of bounds: {} > {}",
+ i, x, offset_limit))
+ ),
+ err => err,
}
+ })
+ .collect::<Result<Vec<usize>>>()?;
Review Comment:
The downside of calling `collect()` is that it will buffer the intermediate result (aka allocate memory and save the offsets in another buffer)
##########
arrow/src/array/data.rs:
##########
@@ -1821,6 +1812,90 @@ mod tests {
.unwrap();
}
+ #[test]
+ fn test_empty_utf8_array_with_empty_offsets_buffer() {
+ let data_buffer = Buffer::from(&[]);
+ let offsets_buffer = Buffer::from(&[]);
+ ArrayData::try_new(
+ DataType::Utf8,
+ 0,
+ None,
+ None,
+ 0,
+ vec![offsets_buffer, data_buffer],
+ vec![],
+ )
+ .unwrap();
+ }
+
+ #[test]
+ fn test_empty_utf8_array_with_single_zero_offset() {
+ let data_buffer = Buffer::from(&[]);
+ let offsets_buffer = Buffer::from_slice_ref(&[0i32]);
+ ArrayData::try_new(
+ DataType::Utf8,
+ 0,
+ None,
+ None,
+ 0,
+ vec![offsets_buffer, data_buffer],
+ vec![],
+ )
+ .unwrap();
+ }
+
+ #[test]
+ #[should_panic(expected = "First offset 1 of Utf8 is larger than values length 0")]
+ fn test_empty_utf8_array_with_invalid_offset() {
+ let data_buffer = Buffer::from(&[]);
+ let offsets_buffer = Buffer::from_slice_ref(&[1i32]);
+ ArrayData::try_new(
+ DataType::Utf8,
+ 0,
+ None,
+ None,
+ 0,
+ vec![offsets_buffer, data_buffer],
+ vec![],
+ )
+ .unwrap();
+ }
+
+ #[test]
+ fn test_empty_utf8_array_with_non_zero_offset() {
+ let data_buffer = Buffer::from_slice_ref(&"abcdef".as_bytes());
+ let offsets_buffer = Buffer::from_slice_ref(&[0i32, 2, 6, 0]);
Review Comment:
yeah, I agree this is strange but ok
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